Breast cancer survivors encounter many stressors that may resulting in lasting, life-altering psychosocial, behavioral, and physiological sequelae. The stressors encountered throughout the course of the disease include, but are not limited to, disruption of life tasks, changes in social network, treatment-related side effects, financial hardship, and uncertainty about disease recurrence and progression. Certainly, the adverse effects of breast cancer have been well documented, but a growing body of literature reveals that some cancer survivors also report positive growth from their experience. At present, little is known about whether or how these potentially life-altering changes negative and positive can be influenced by psychosocial interventions. That is, how, if all, do psychosocial interventions buffer the negative effects of breast cancer and its treatment? How do such interventions enhance positive growth in survivors? Moreover, how do intervention-related processed influence physiological changes (i.e., in behavior, immune system functioning, and neuroendocrine functioning), which in turn, may increased or reduce the risk of breast cancer recurrence and progression? These questions are the focus of the proposed project. We propose to test the effectiveness of our group-based, cognitive behavioral stress management (CBSM intervention among White, Hispanic, and Black women who have been diagnosed with and treated for primary, early- to middle stage breast cancer (Stages I-III). The proposed project will examine the effects of CBSM on a variety of psychosocial processes (i.e., cognitive appraisals, self-efficacy, social support, and physiological arousal) immediately, 6 months, and 12 months after the intervention. Specifically, we expect intervention-related changes in these processes to foster a more rapid return to pre-diagnostic levels of quality of life, as well as enhance a sense of positive growth. We will also examine how intervention-related changes in these processes are associated with changes in health behaviors, immune system functioning, and reproductive hormone levels, which themselves may be related to disease recurrence and progression.